近日，美国杜克大学Kenichi Yokoyama团队研究了非血红素铁依赖性酶的氮杂苷氨基酸生物合成。该项研究成果发表在2025年10月21日出版的《自然-化学》杂志上。

氮杂环是一个四元氮杂环，是许多生物活性化合物和药物的重要结构。然而，它们的生物合成常常是神秘的。

研究组报道了氮杂啶氨基酸（多肟酸）生物合成在多毒素抗真菌途径中的作用机制。遗传、酶学和结构实验表明，PolF是血红加氧酶样二金属氧化酶和/或加氧酶（HDO）超家族的成员，该酶本身就足以通过3,4-去饱和中间体将l -异亮氨酸（L-Ile）和l -缬氨酸转化为它们的氮杂啶衍生物。

对PolF的机理研究表明，μ-过氧化物-Fe(III)₂中间体直接导致了未活化的C-H键断裂，而H萃取后的反应，包括C-N键的形成，可能是通过自由基机制进行的。研究组还发现，作为DUF6421家族的一员，PolE是一种铁和蝶呤依赖的氧化酶，它可以催化L-Ile的去饱和，通过增加L-Ile的去饱和通量来辅助PolF。这些结果为氮杂胞苷的生物合成和HDO酶的催化机制提供了重要的见解。

附：英文原文

Title: Azetidine amino acid biosynthesis by non-haem iron-dependent enzymes

Author: Du, Yanan, Thanapipatsiri, Anyarat, Blancas Cortez, Jess J., Salas-Sol, Xavier E., Lin, Chi-Yun, Boal, Amie K., Krebs, Carsten, Bollinger, J. Martin, Yokoyama, Kenichi

Issue&Volume: 2025-10-21

Abstract: Azetidine, a four-membered aza-cycle, is a crucial structure in many bioactive compounds and drugs. However, their biosynthesis is frequently enigmatic. Here we report the mechanism of azetidine amino acid (polyoximic acid) biosynthesis in the polyoxin antifungal pathway. Genetic, enzymological and structural experiments revealed that PolF is a member of haem-oxygenase-like dimetal oxidase and/or oxygenase (HDO) superfamily, and this enzyme alone is sufficient for the transformation of L-isoleucine (L-Ile) and L-valine to their azetidine derivatives via a 3,4-desaturated intermediate. Mechanistic studies of PolF suggested that a μ-peroxo-Fe(III)2 intermediate is directly responsible for the unactivated C–H bond cleavage, and the post-H-abstraction reactions, including the C–N bond formation, probably proceed through radical mechanisms. We also found that PolE, a member of the DUF6421 family, is an Fe and pterin-dependent oxidase that catalyses the desaturation of L-Ile, assisting PolF by increasing the flux of L-Ile desaturation. The results provide important insights into azetidine biosynthesis and the catalytic mechanisms of HDO enzymes in general.

DOI: 10.1038/s41557-025-01958-x

Source: https://www.nature.com/articles/s41557-025-01958-x